#DNS
VM Sees the Dongle but Has No Internet Without a Windows ECM Driver
After passing a USB LTE dongle through to a Windows VM, the system sees the device but no network adapter appears. The cause is neither the SIM nor port passthrough, but the dongle exposing a CDC ECM interface that Windows has no built-in driver for, along with storage-mode pitfalls and dhclient overwriting the host's resolv.conf.
Registrar and Billing NS Mismatch: Audit All Three Sides First
A debugging log for "Wrong response from the server" when changing nameservers in a billing system, which failed only for domains with leftover glue IP data, followed by a three-way audit of the registrar, billing system, and actual DNS zones before I felt confident changing anything.
Egress Firewall Breaks Domain Checks — Tests as root Pass
The domain order page reported every name as unavailable, even names I made up. The cause was an outbound DROP policy with port 43 missing from the allowed port list after an operating system migration. The trap was that tests as root passed every time. Testing must use the account that actually runs the app.
Static on DirectAdmin: GET Returns 404 but HEAD Returns 200
I uploaded a static site to public_html and could not open it. Small files worked, large files returned 404, but HEAD returned 200 for every file. The cause was Laravel's .htaccess at the docroot, funneling everything into the front controller. This article covers the diagnosis and three ways out.
Screenshot Multiple Domains Directly from Origin, Bypassing Cloudflare
Need screenshots of dozens of domains for inspection, or want to confirm that the origin server (not the CDN cache) renders correctly — but Chrome's screenshot flag has been broken since version 132, and AV reverts hosts edits? This article uses Playwright to override DNS at the process level, solving both problems.
Mail Stopped After Moving to Cloudflare — Proxied Mail Records
After adding a domain to Cloudflare and pointing DNS at the host, incoming mail suddenly stops — the most common cause I see is leaving mail/smtp/pop records proxied (orange cloud), even though Cloudflare's proxy only handles HTTP/S. This article covers which records must be grey + token/SSL pitfalls.
AdSense Says ads.txt Is Missing: Tracing the Logs Layer by Layer
The AdSense Sites page reports ads.txt as "Not found" even though the file exists and is correct — a forensic investigation using curl + access logs to prove, layer by layer, whether Googlebot visited and what it received. Case closed: nothing was blocking it; Google's own status was stale.
Lost the .com: Move to .net on DirectAdmin Without Data Loss
A .com domain expired and ended up with a domain squatter — how I moved the whole site (files/mail/DNS/SSL) to a new .net domain on DirectAdmin with a single CMD_CHANGE_DOMAIN command, plus 4 follow-up tasks that do not happen automatically
Moving DA from CentOS 7 to Debian 12, Part 4 — Cutover and 17 Issues
The actual cutover, where the near-0 downtime plan fell apart because of the DA Legacy license and slow qcow2 reads, ended with 1 hour of downtime and 17 issues in quick succession after the switch — critical web stack outages, medium issues affecting subsets of services, and minor debugging notes.